U.S. patent application number 11/954521 was filed with the patent office on 2008-04-03 for antenna device and wireless communication apparatus.
This patent application is currently assigned to MURATA MANUFACTURING CO., LTD.. Invention is credited to Kenichi Ishizuka, Kazunari Kawahata.
Application Number | 20080079642 11/954521 |
Document ID | / |
Family ID | 37532070 |
Filed Date | 2008-04-03 |
United States Patent
Application |
20080079642 |
Kind Code |
A1 |
Ishizuka; Kenichi ; et
al. |
April 3, 2008 |
ANTENNA DEVICE AND WIRELESS COMMUNICATION APPARATUS
Abstract
A compact and thin antenna device can be mounted in a small area
of a substrate and has a multiband capability adaptable to various
applications. The antenna device includes a chip antenna, an
antenna element, and a chip antenna. The chip antenna is produced
by forming a radiation electrode on the surface of a dielectric
base, and mounting a frequency variable circuit on the radiation
electrode. Thus, it becomes possible to obtain a resonant frequency
f1 of the chip antenna and further to vary the resonant frequency
f1. The antenna element is produced by adding an auxiliary element
to an additional radiation electrode for the chip antenna. The chip
antenna includes a radiation electrode on a dielectric base and a
conductive pattern. Thus, a resonant frequency f2 and a resonant
frequency f3 of the antenna element and the chip antenna,
respectively, can be obtained.
Inventors: |
Ishizuka; Kenichi;
(Sagamihara-shi, JP) ; Kawahata; Kazunari;
(Machida-shi, JP) |
Correspondence
Address: |
MURATA MANUFACTURING COMPANY, LTD.;C/O KEATING & BENNETT, LLP
8180 GREENSBORO DRIVE
SUITE 850
MCLEAN
VA
22102
US
|
Assignee: |
MURATA MANUFACTURING CO.,
LTD.
Nagaokakyo-shi
JP
|
Family ID: |
37532070 |
Appl. No.: |
11/954521 |
Filed: |
December 12, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2006/306701 |
Mar 30, 2006 |
|
|
|
11954521 |
Dec 12, 2007 |
|
|
|
Current U.S.
Class: |
343/702 ;
343/700MS |
Current CPC
Class: |
H01Q 1/243 20130101;
H01Q 1/38 20130101; H01Q 9/42 20130101; H01Q 5/371 20150115 |
Class at
Publication: |
343/702 ;
343/700.0MS |
International
Class: |
H01Q 1/24 20060101
H01Q001/24 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 17, 2005 |
JP |
2005-177764 |
Claims
1. An antenna device comprising: a first chip antenna including a
first radiation electrode and a frequency variable circuit arranged
to vary an electrical length of the first radiation electrode
provided on a dielectric or magnetic base mounted on an upper side
of a non-ground region of a substrate; at least one antenna element
including an additional radiation electrode provided on the base of
the first chip antenna and an auxiliary element disposed on the
upper side or an underside of the non-ground region and connected
to the additional radiation electrode, and having a predetermined
electrical length; and a second chip antenna including a second
radiation electrode disposed on the dielectric or magnetic base
mounted on the upper side or underside of the non-ground region of
the substrate, and having a predetermined electrical length.
2. The antenna device according to claim 1, wherein the antenna
element includes the auxiliary element disposed on the underside of
the non-ground region connected to the additional radiation
electrode through a through hole provided in the non-ground
region.
3. The antenna device according to claim 1, wherein the number of
the antenna elements is more than one, and all resonant frequencies
of the plurality of antenna elements are different.
4. The antenna device according to claim 1, wherein the auxiliary
element of the antenna element is a planar electrode including a
conductive pattern provided in the non-ground region.
5. The antenna device according to claim 1, wherein the auxiliary
element of the antenna element is a three-dimensional electrode
including a supporting portion vertically disposed in the
non-ground region while being connected to the additional radiation
electrode, and a parallel portion extending substantially parallel
to the substrate from an end of the supporting portion.
6. The antenna device according to claim 5, wherein the parallel
portion of the auxiliary element is strip-shaped.
7. The antenna device according to claim 5, wherein the parallel
portion of the auxiliary element has a flat plate-shaped
configuration.
8. The antenna device according to claim 5, wherein the parallel
portion of the auxiliary element does not extend beyond the
non-ground region.
9. The antenna device according to claim 5, wherein an end of the
parallel portion of the auxiliary element is an open end.
10. The antenna device according to claim 1, wherein the auxiliary
element disposed on the underside of the non-ground region is
disposed on the dielectric or magnetic base mounted on the
underside.
11. The antenna device according to claim 1, wherein a feeding
element for the second chip antenna differs from that for the first
chip antenna.
12. A wireless communication apparatus comprising an antenna device
according to claim 1.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an antenna device for use
in mobile phones or the like, and also to a wireless communication
apparatus.
[0003] 2. Description of the Related Art
[0004] In recent years, as the size of a wireless communication
apparatus, such as a mobile phone, has decreased and density
therein has increased, it is becoming necessary that an antenna
device be mounted in a small area of a substrate.
[0005] However, mounting an antenna device in a small area requires
a reduction in the size and thickness of the antenna device, and
thus may degrade the antenna characteristics.
[0006] Therefore, for example, as disclosed in Japanese Unexamined
Patent Application Publication No. 2000-114992, Japanese Unexamined
Patent Application Publication No. 2004-023210, Japanese Unexamined
Utility Model Registration Application Publication No. 07-020708,
and Japanese Unexamined Patent Application Publication No.
2004-128605, various types of antenna devices having been made
smaller and thinner without degrading the antenna characteristics
have been proposed. Additionally, frequency variation techniques
and an active antenna integral with an amplifier have been
developed.
[0007] An antenna device disclosed in Japanese Unexamined Patent
Application Publication No. 2000-114992 is an antenna having a loop
radiation electrode. By connecting radiation electrodes formed on
the upper and lower surfaces of a substrate through a through hole,
the entire antenna is formed into a loop. A compact antenna device
with improved radio radiation characteristics can thus be
achieved.
[0008] An antenna device disclosed in Japanese Unexamined Patent
Application Publication No. 2004-023210 is a dipole antenna in
which two antenna elements are arranged to form a single plane, and
power is fed to the two antenna elements in a balanced manner. This
contributes to the prevention of noise and the reduced thickness of
the antenna device.
[0009] An antenna device disclosed in Japanese Unexamined Utility
Model Registration Application Publication No. 07-020708 is a coil
antenna. The characteristics of a coil antenna largely depend on
its thickness (specifically, the diameter of a winding core). In
this antenna device, therefore, the coil antenna is inserted into a
hole provided in a substrate. This reduces the thickness of the
entire antenna device without degrading the antenna
characteristics.
[0010] An antenna device disclosed in Japanese Unexamined Patent
Application Publication No. 2004-128605 is a quarter-wavelength
patch antenna or an inverted F antenna. The characteristics of such
an antenna are largely influenced by the distance from a ground
surface of a substrate to a radiation electrode. Therefore, in this
antenna device, the radiation electrode of the antenna is extended
from the upper side to the underside of the substrate at an end
thereof. This reduces the thickness of the entire antenna device
without degrading the antenna characteristics.
[0011] Other antenna devices similar to those described above are
disclosed in Japanese Unexamined Patent Application Publication No.
08-023218 and Japanese Unexamined Patent Application Publication
No. 2004-165770.
[0012] However, known antenna devices described above have the
following problems.
[0013] Since the antenna device disclosed in Japanese Unexamined
Patent Application Publication No. 2000-114992 is a loop antenna, a
larger loop diameter increases dead space. Moreover, since the loop
antenna is composed of a radiation electrode formed on the upper
and lower surfaces of the substrate, the dead space extends not
only over one surface but also over both surfaces of the substrate.
This creates dead space that is double or more than double the
normal amount. Furthermore, if the design of, for example, a
housing of a wireless communication apparatus is altered, the
radiation electrode of the antenna needs to be totally
redesigned.
[0014] The antenna device disclosed in Japanese Unexamined Patent
Application Publication No. 2004-023210 is a dipole antenna in
which two antenna elements are arranged to form a single plane.
Although the thickness of the device can be reduced in this case,
it is not possible to reduce the size of the entire device.
Moreover, since alignment including the balancing of feeding parts
in the antenna device is very complicated, design work for the
alignment takes a long time.
[0015] To produce an antenna device disclosed in Japanese
Unexamined Utility Model Registration Application Publication No.
07-020708 or Japanese Unexamined Patent Application Publication No.
2004-128605, it is required that a coil antenna be inserted into a
hole provided in a substrate or a radiation electrode be extended
from the upper side to the underside of a substrate at an end
thereof. This involves difficult alignment of both configurations
and antenna characteristics.
[0016] Japanese Unexamined Patent Application Publication No.
2000-114992, Japanese Unexamined Patent Application Publication No.
2004-023210, Japanese Unexamined Utility Model Registration
Application Publication No. 07-020708, and Japanese Unexamined
Patent Application Publication No. 2004-128605 are discussed on the
assumption that the disclosed antennas are single resonance
antennas. Therefore, if a multiple-resonance antenna device or a
frequency-variable antenna device is produced with any one of the
techniques described above, dead space that is double or more than
double the normal amount is created or the size of the antenna
device increases. In other words, it is virtually impossible to
incorporate such an antenna device into a wireless communication
apparatus, where compactness and high board density are required.
Similar problems arise in the antenna devices disclosed in Japanese
Unexamined Patent Application Publication No. 08-023218 and
Japanese Unexamined Patent Application Publication No.
2004-165770.
SUMMARY OF THE INVENTION
[0017] In order to overcome the problems described above, preferred
embodiments of the present invention provide a compact and thin
antenna device that can be mounted in a small area of a substrate
and has a multiband capability adaptable to various applications,
and provide a wireless communication apparatus.
[0018] An antenna device according to a preferred embodiment of the
present invention includes a first chip antenna including a first
radiation electrode and a frequency variable circuit arranged to
vary an electrical length of the first radiation electrode that are
provided on a dielectric or magnetic base mounted on an upper side
of a non-ground region of a substrate; at least one antenna element
including an additional radiation electrode provided on the base of
the first chip antenna and an auxiliary element disposed on the
upper side or an underside of the non-ground region and connected
to the additional radiation electrode, and having a predetermined
electrical length; and a second chip antenna including a second
radiation electrode disposed on the dielectric or magnetic base
mounted on the upper side or underside of the non-ground region of
the substrate, and having a predetermined electrical length.
[0019] These antennas interfere with each other, generate a
plurality of resonant frequencies, and are capable of sending and
receiving a plurality of signals at different frequencies.
Moreover, since the auxiliary element of the antenna element is
disposed on one or both the upper side and underside of the
non-ground region, it is possible to reduce dead space and the size
of the entire antenna device, and further to improve antenna
characteristics.
[0020] The antenna element is preferably formed by connecting the
auxiliary element disposed on the underside of the non-ground
region to the additional radiation electrode through a through hole
provided in the non-ground region.
[0021] The number of the antenna elements preferably is more than
one, and all resonant frequencies of the plurality of antenna
elements are preferably different.
[0022] The auxiliary element of the antenna element preferably is a
planar electrode produced by forming a conductive pattern in the
non-ground region.
[0023] The auxiliary element of the antenna element preferably is a
three-dimensional electrode including a supporting portion
vertically disposed in the non-ground region while being connected
to the additional radiation electrode, and a parallel portion
extending substantially parallel to the substrate from an end of
the supporting part.
[0024] With this configuration, since the auxiliary element of the
antenna element is a three-dimensional electrode, it is possible to
effectively extend the electrode spatially, as well as
horizontally.
[0025] The parallel portion of the auxiliary element preferably is
strip-shaped.
[0026] The parallel portion of the auxiliary element preferably is
in the shape of a flat plate.
[0027] The size of the parallel portion of the auxiliary element is
set such that the parallel portion does not extend beyond the
non-ground region.
[0028] An end of the parallel portion of the auxiliary element
preferably is an open end.
[0029] The auxiliary element disposed on the underside of the
non-ground region is disposed on the dielectric or magnetic base
mounted on the underside.
[0030] With this configuration, since the base on which the
auxiliary element is disposed is made of dielectric material or the
like having a wavelength reduction effect, it is possible to adjust
the resonant frequency of the antenna element.
[0031] A feeding element for the second chip antenna is preferably
different from that for the first chip antenna.
[0032] A wireless communication apparatus according to another
preferred embodiment of the present invention includes an antenna
device according to the above-described preferred embodiments.
[0033] With an antenna device according to various preferred
embodiments of the present invention, signals at different resonant
frequencies can be sent and received by the first chip antenna, at
least one antenna element, and the second chip antenna. In other
words, the antenna device is configured to allow multiple
resonance. Therefore, an antenna device having the capability of
multiband transmission and reception, and thus adaptable to various
applications can be provided. Moreover, since the auxiliary element
of the antenna element is disposed on one or both of the upper side
and underside of the non-ground region, it is possible to reduce
dead space and the size of the entire antenna device without
degrading antenna performance.
[0034] In particular, by disposing the auxiliary element of the
antenna element on the underside of the non-ground region, the
antenna volume of the entire antenna device, including the first
and second chip antennas and the antenna element, can be
efficiently increased. In other words, by disposing the auxiliary
element on the underside of the non-ground region where there is
virtually no limitation on the electrode shape and size, an antenna
volume larger than that of known antennas can be obtained.
[0035] Moreover, since alignment in the antenna device is easy,
design work for the alignment can be completed in a short time.
[0036] With an antenna device according to various preferred
embodiments of the present invention, the auxiliary element of the
antenna element preferably is a three-dimensional electrode and
thus can be effectively used spatially, as well as horizontally.
Therefore, it is possible to realize an antenna device that uses
not only space near the non-ground region, but all dead space in
the housing of the apparatus in which the antenna device is
incorporated. For example, it is possible to form the auxiliary
element to fit the outline of a wireless communication apparatus,
such as a mobile phone.
[0037] With the antenna device according to a preferred embodiment
of the present invention, since the base made of dielectric
material or the like having a wavelength reduction effect enables
the adjustment of the resonant frequency of the antenna element, it
is possible to provide an antenna device having the capability of
multiband transmission over a wider band.
[0038] With the wireless communication apparatus according to a
preferred embodiment of the present invention, it is possible to
provide a compact and thin multiband wireless communication
apparatus.
[0039] Other features, elements, processes, steps, characteristics
and advantages of the present invention will become more apparent
from the following detailed description of preferred embodiments of
the present invention with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] FIG. 1 is a perspective view illustrating the upper side of
an antenna device according to a first preferred embodiment of the
present invention.
[0041] FIG. 2 is a plan view of a first chip antenna developed
along sides thereof.
[0042] FIG. 3 is an equivalent circuit diagram of a frequency
variable circuit.
[0043] FIG. 4 is a cutaway side view of the antenna device.
[0044] FIG. 5 is a perspective view for illustrating an overall
configuration of an auxiliary element of an antenna element.
[0045] FIG. 6 is a plan view of a second chip antenna developed
along sides thereof.
[0046] FIG. 7 is a perspective view for illustrating a conductive
pattern.
[0047] FIG. 8 is a perspective view for illustrating an overall
configuration of the first chip antenna.
[0048] FIG. 9 is a perspective view for illustrating an overall
configuration of the antenna element.
[0049] FIG. 10 is a perspective view for illustrating an overall
configuration of the second chip antenna.
[0050] FIG. 11 is a diagram for describing a state of multiple
resonance.
[0051] FIG. 12 is a simplified plan view illustrating a state in
which substrates of a foldable wireless communication apparatus are
housed.
[0052] FIG. 13 is a perspective view illustrating the upper side of
an antenna device according to a second preferred embodiment of the
present invention.
[0053] FIG. 14 is a plan view illustrating the underside of the
antenna device.
[0054] FIG. 15 is a cutaway side view of the antenna device.
[0055] FIG. 16 is a perspective view illustrating the upper side of
an antenna device according to a third preferred embodiment of the
present invention.
[0056] FIG. 17 illustrates the underside of the antenna device.
[0057] FIG. 18 is a cutaway side view of the antenna device.
[0058] FIG. 19 is a perspective view illustrating the upper side of
an antenna device according to a fourth preferred embodiment of the
present invention.
[0059] FIG. 20 is a plan view illustrating the underside of the
antenna device.
[0060] FIG. 21 is a perspective view illustrating a dielectric
base.
[0061] FIG. 22 is a perspective view illustrating the upper side of
an antenna device according to a fifth preferred embodiment of the
present invention.
[0062] FIG. 23 is a perspective view of a second chip antenna.
[0063] FIG. 24 is a perspective view illustrating the underside of
the antenna device.
[0064] FIG. 25 is an exploded perspective view of an antenna device
according to a sixth preferred embodiment of the present
invention.
[0065] FIG. 26 is a diagram illustrating a state of quadruple
resonance.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0066] Preferred embodiments and best modes for carrying out the
present invention will now be described with reference to the
drawings.
First Preferred Embodiment
[0067] FIG. 1 is a perspective view illustrating the upper side of
an antenna device according to a first preferred embodiment of the
present invention. FIG. 2 is a plan view of a first chip antenna
developed along sides thereof. FIG. 3 is an equivalent circuit
diagram of a frequency variable circuit.
[0068] An antenna device 1 of the present preferred embodiment is
mounted on a wireless communication apparatus, such as a mobile
phone.
[0069] As illustrated in FIG. 1, the antenna device 1 includes a
chip antenna 2 serving as a first chip antenna, an antenna element
3, and a chip antenna 4 serving as a second chip antenna.
[0070] The chip antenna 2 is a surface-mount chip antenna produced
by forming a radiation electrode 21 serving as a first radiation
electrode, and a frequency variable circuit 22 on the surface of a
dielectric base 20.
[0071] Aground region 101 and a non-ground region 102 are disposed
on both surfaces of a substrate 100, while the dielectric base 20
of the chip antenna 2 is mounted on an upper side 102a of the
non-ground region 102. Specifically, as illustrated in FIG. 2, the
dielectric base 20 preferably has a substantially rectangular
parallel piped shape and has a front surface 20a, an upper surface
20b, both side surfaces 20c and 20d, a back surface 20e, and a
lower surface 20f.
[0072] The radiation electrode 21 is a strip of constant width and
includes a front electrode section 21a, an upper electrode section
21b, and an end electrode section 21c. Specifically, the front
electrode section 21a is formed on the left edge of the front
surface 20a of the dielectric base 20 and, as illustrated in FIG.
1, one end of the front electrode section 21a is connected to a
power feeder 110 (power feeding means) through a conductive pattern
111. Then, as illustrated in FIG. 2, the other end of the front
electrode section 21a is connected to the upper electrode section
21b, which is connected to the end electrode section 21c formed on
the front surface 20a.
[0073] In other words, as illustrated in FIG. 1 and FIG. 2, the
radiation electrode 21 of the chip antenna 2 has a structure in
which the front electrode section 21a is connected to the power
feeder 110 through the conductive pattern 111, the upper electrode
section 21b and the end electrode section 21c are connected to the
front electrode section 21a, and the frequency variable circuit 22
is mounted on the upper electrode section 21b.
[0074] As illustrated in FIG. 2 and FIG. 3, the frequency variable
circuit 22 is a series circuit of a coil 22a, a
variable-capacitance diode 22b, a capacitor 22c, and a coil 22d.
The frequency variable circuit 22 is configured such that a pattern
22f including a coil 22e is connected to a connection point P
between the variable-capacitance diode 22b and the capacitor 22c.
Thus, by applying a control voltage Vc to the connection point P
through the pattern 22f and controlling the capacitance of the
variable-capacitance diode 22b, the electrical length of the
radiation electrode 21 can be varied.
[0075] The antenna element 3 includes, as illustrated in FIG. 1, a
strip-shaped additional radiation electrode 30 and an auxiliary
element 31 connected to the additional radiation electrode 30.
[0076] FIG. 4 is a cutaway side view of the antenna device. FIG. 5
is a perspective view for illustrating an overall configuration of
the auxiliary element of the antenna element 3.
[0077] As illustrated in FIG. 2, the additional radiation electrode
30 includes an upper electrode 30b that branches from the front
electrode section 21a of the radiation electrode 21 on the upper
surface 20b of the dielectric base 20, and a side electrode 30c and
a connecting electrode 30f formed on the side surface 20c and the
lower surface 20f, respectively, so as to extend from the upper
electrode 30b.
[0078] As illustrated in FIG. 4, the auxiliary element 31 is
disposed on an underside 102b of the non-ground region 102, and
connected to the additional radiation electrode 30 through a
through hole 102c provided in the non-ground region 102.
[0079] Specifically, as illustrated in FIG. 4 and FIG. 5, the
auxiliary element 31 is a three-dimensional electrode including a
metal support 31a serving as a supporting portion and a metal sheet
31b serving as a parallel portion. The through hole 102c is
provided in the non-ground region 102 and located at a point
corresponding to the connecting electrode 30f of the additional
radiation electrode 30. The metal support 31a in the shape of a rod
is vertically disposed on the underside 102b of the non-ground
region 102 while being in the through hole 102c. The metal sheet
31b is connected to an end of the metal support 31a and held to be
substantially parallel to the substrate 100. The metal sheet 31b
preferably is a flat, substantially rectangular metal plate that is
smaller in size than the non-ground region 102 and is designed not
to extend beyond the non-ground region 102. The metal sheet 31b is
not in contact with the ground region 101 at any point, and all the
edges of the metal sheet 31b are open ends.
[0080] As illustrated in FIG. 1, the chip antenna 4 includes a
dielectric base 40 mounted on the upper side 102a of the non-ground
region 102 in the substrate 100, and a radiation electrode 41
serving as a second radiation electrode.
[0081] FIG. 6 is a developed view of the chip antenna 4. FIG. 7 is
a perspective view for illustrating a conductive pattern.
[0082] As illustrated in FIG. 6, the dielectric base 40 preferably
has a substantially rectangular parallelepiped shape and has a
front surface 40a, an upper surface 40b, both side surfaces 40c and
40d, a back surface 40e, and a lower surface 40f.
[0083] The radiation electrode 41 includes a front electrode
section 41a, a substantially L-shaped upper electrode section 41b,
and a side electrode section 41c. One end of the front electrode
section 41a is, as illustrated in FIG. 1, connected through a
conductive pattern 41g to the conductive pattern 111. That is, as
illustrated in FIG. 7, the conductive pattern 41g is formed on the
underside 102b of the non-ground region 102, and both ends of the
conductive pattern 41g are connected via through holes 102d and
102e to the front electrode section 41a and the conductive pattern
111, respectively.
[0084] Thus, the radiation electrode 41 of the chip antenna 4 is
connected to the power feeder 110 through the conductive pattern
41g and the conductive pattern 111, and has a fixed electrical
length of the entire chip antenna 4.
[0085] Next, functions and effects of the antenna device of the
present preferred embodiment will be described.
[0086] FIG. 8 is a perspective view for illustrating an overall
configuration of the chip antenna 2. FIG. 9 is a perspective view
for illustrating an overall configuration of the antenna element 3.
FIG. 10 is a perspective view for illustrating an overall
configuration of the chip antenna 4. FIG. 11 is a diagram for
describing a state of multiple resonance. FIG. 12 is a simplified
plan view illustrating a state in which substrates of a foldable
wireless communication apparatus are housed.
[0087] As illustrated in FIG. 8, the chip antenna 2 has an
electrical length corresponding to the lengths and shapes of the
radiation electrode 21 and the conductive pattern 111. The resonant
frequency of the chip antenna 2 can be varied by the frequency
variable circuit 22. Since the chip antenna 2 is used in
combination with the antenna element 3 and the chip antenna 4, the
actual resonant frequency of the chip antenna 2 is different from
the resonant frequency of the chip antenna 2 alone. The actual
resonant frequency, which is set at f1, can be varied widely by the
frequency variable circuit 22.
[0088] As illustrated in FIG. 9, the antenna element 3 has an
electrical length corresponding to the lengths and shapes of the
additional radiation electrode 30, the auxiliary element 31, and
the conductive pattern 111. Since the antenna element 3 is used in
combination with the chip antenna 2 and the chip antenna 4, the
actual resonant frequency of the antenna element 3 is different
from the resonant frequency of the antenna element 3 alone. The
actual resonant frequency, which is set at f2 and is substantially
constant, changes slightly when the frequency variable circuit 22
of the chip antenna 2 widely varies the resonant frequency f1.
[0089] As illustrated in FIG. 10, the chip antenna 4 has an
electrical length corresponding to the lengths and shapes of the
radiation electrode 41, the conductive pattern 41g, and the
conductive pattern 111. Since the chip antenna 4 is used in
combination with the chip antenna 2 and the antenna element 3, the
actual resonant frequency of the chip antenna 4 is different from
the resonant frequency of the chip antenna 4 alone. This actual
resonant frequency, which is set at f3 and is substantially
constant, changes slightly when the frequency variable circuit 22
of the chip antenna 2 widely varies the resonant frequency f1.
[0090] Thus, as illustrated in FIG. 11, the antenna device 1 has
three resonant frequencies f1, f2, and f3. As indicated by arrows,
the resonant frequency f1 can be widely varied and the resonant
frequencies f2 and f3 can be slightly varied.
[0091] Therefore, when the antenna device 1 is incorporated into a
wireless communication apparatus 200 as illustrated in FIG. 12, and
a signal of frequency f1 is supplied from the power feeder 110 to
the antenna device 1 in FIG. 1, the supplied signal resonates with
the chip antenna 2, as the actual resonant frequency of the chip
antenna 2 is set at f1 as described above. As a result, this signal
is transmitted as a radio wave from the entire antenna device 1,
mainly from the chip antenna 2, into space. A radio wave of
frequency f1 is received by the entire antenna device 1, mainly by
the chip antenna 2. Thus, the antenna device 1 of the present
preferred embodiment can send and receive a signal of frequency f1
by using mainly the chip antenna 2.
[0092] If a signal of frequency f2 is supplied from the power
feeder 110 to the antenna device 1, the supplied signal resonates
with the antenna element 3, as the resonant frequency of the
antenna element 3 is set at f2 as described above. As a result,
this signal is transmitted as a radio wave from the entire antenna
device 1, mainly from the antenna element 3, into space. A radio
wave of frequency f2 is received by the entire antenna device 1,
mainly by the antenna element 3. Thus, the antenna device 1 of the
present preferred embodiment can send and receive a signal of
frequency f2 by using mainly the antenna element 3.
[0093] If a signal of frequency f3 is supplied from the power
feeder 110 to the antenna device 1, the supplied signal resonates
with the chip antenna 4, as the resonant frequency of the chip
antenna 4 is set at f3 as described above. As a result, this signal
is transmitted as a radio wave from the entire antenna device 1,
mainly from the antenna element 3, into space. A radio wave of
frequency f3 is received by the entire antenna device 1, mainly by
the chip antenna 4. Thus, the antenna device 1 of the present
preferred embodiment can send and receive a signal of frequency f3
by using mainly the chip antenna 4.
[0094] As described above, the antenna device 1 of the present
preferred embodiment is configured such that signals at three
different resonant frequencies f1 to f3 can be sent and received by
the chip antenna 2, the antenna element 3, and the chip antenna 4.
Therefore, it is possible to provide a multiband transmission
capability adaptable to various applications. That is, as
illustrated in FIG. 11, a return loss curve S showing the lowest
return loss at three different frequencies f1 to f3 can be
obtained. For example, if the resonant frequency f1 of the chip
antenna 2 is set at about 800 MHz, the antenna device 1 can be used
for an application such as a mobile phone. At the same time, if the
resonant frequency f2 of the antenna element 3 is set at about 1.6
GHz, the antenna device 1 can also be used for an application such
as a global positioning system (GPS).
[0095] Moreover, in the present preferred embodiment, the auxiliary
element 31 of the antenna element 3 is disposed on the underside
102b of the non-ground region 102, so as to form the antenna device
1 by using the underside 102b as well as the upper side 102a of the
non-ground region 102. Therefore, dead space and the size of the
entire antenna device 1 can be reduced without degrading antenna
performance. Furthermore, since the auxiliary element 31 is a
three-dimensional electrode effectively extended spatially (in the
height direction) as well as horizontally, an antenna volume that
is much larger than that of a known antenna device can be obtained
in a small space.
[0096] As illustrated in FIG. 12, the wireless communication
apparatus 200 of foldable type in particular has a structure in
which two substrates 211 and 212 are housed in an upper housing 201
and an lower housing 202, respectively. If known techniques are
used to produce a multiple-resonance antenna device, an antenna
element 301 corresponding to the chip antennas 2 and 4 needs to be
mounted in a non-ground region 211a of the substrate 211, while an
antenna element 302 corresponding to the antenna element 3 needs to
be mounted in a non-ground region 212a of the substrate 212. On the
other hand, since the antenna device 1 of the present embodiment
requires only the non-ground region 102 of the substrate 100 as a
mounting area, the amount of space taken up by the antenna device
can be reduced to half or less than half that in the case of a
known antenna device. Moreover, although a large amount of dead
space is created on the undersides of the non-ground regions 211a
and 212a in the known antenna device, virtually no such dead space
is created in the case of the present preferred embodiment.
[0097] Furthermore, since, in the present preferred embodiment, the
antenna element 3 includes the radiation electrode 21 disposed on
the dielectric base 20 of the chip antenna 2 and the auxiliary
element 31, the number of components of the antenna device 1 is
smaller than that of the known antenna device, where the chip
antenna 2 and the antenna element 3 have to be formed on different
substrates.
Second Preferred Embodiment
[0098] FIG. 13 is a perspective view illustrating the upper side of
an antenna device according to a second preferred embodiment of the
present invention. FIG. 14 is a plan view illustrating the
underside of the antenna device. FIG. 15 is a cutaway side view of
the antenna device.
[0099] As illustrated in FIG. 13 to FIG. 15, in the antenna device
of the present preferred embodiment, an auxiliary element 31 of an
antenna element 3 includes a metal support 31a and a strip-shaped
metal sheet 31b.
[0100] Specifically, the entire strip-shaped metal sheet 31b
preferably has a substantially U-shaped configuration, and one end
of the metal sheet 31b is connected to one end of the metal support
31a such that the entire metal sheet 31b is disposed over an
underside 102b of a non-ground region 102.
[0101] With this configuration, the antenna element 3 can
contribute to improved characteristics of the antenna device 1 and
can establish another resonance.
[0102] The other configurations, functions, and effects are similar
to those of the first preferred embodiment and thus will not be
described here.
Third Preferred Embodiment
[0103] FIG. 16 is a perspective view illustrating the upper side of
an antenna device according to a third preferred embodiment of the
present invention. FIG. 17 illustrates the underside of the antenna
device. FIG. 18 is a cutaway side view of the antenna device.
[0104] As illustrated in FIG. 16, in the antenna device of the
present preferred embodiment, an auxiliary element 31 of an antenna
element 3 is a planar electrode.
[0105] In other words, as illustrated in FIG. 17 and FIG. 18, the
auxiliary element 31 including an extraction pattern 31a and a
strip-like hook-shaped conductive pattern 31b having ends extending
in opposite directions is disposed on an underside 102b of a
non-ground region 102. Specifically, the extraction pattern 31a of
the auxiliary element 31 is connected to a connecting electrode 30f
of an additional radiation electrode 30 through a through hole
102c.
[0106] This configuration contributes to the improved
characteristics and reduced thickness of the antenna device 1.
[0107] The other configurations, functions, and effects are similar
to those of the first preferred embodiment and thus will not be
described here.
Fourth Preferred Embodiment
[0108] FIG. 19 is a perspective view illustrating the upper side of
an antenna device according to a fourth preferred embodiment of the
present invention. FIG. 20 is a plan view illustrating the
underside of the antenna device. FIG. 21 is a perspective view
illustrating a dielectric base.
[0109] In the third preferred embodiment described above, the
conductive pattern 31b of the auxiliary element 31 of the antenna
element 3 is formed directly on the non-ground region 102. In the
present preferred embodiment, as illustrated in FIG. 19 to FIG. 21,
an auxiliary element 31 of an antenna element 3 is disposed on a
dielectric base 7.
[0110] Specifically, as illustrated in FIG. 21, a pattern of the
auxiliary element 31 is arranged over the lower surface, back
surface, and upper surface of the dielectric base 7, which
preferably has a substantially rectangular parallelepiped shape.
Then, the auxiliary element 31 is connected to an additional
radiation electrode 30 by mounting the dielectric base 7 on an
underside 102b of a non-ground region 102 while an end 31a on the
upper surface of the dielectric base 7 is in contact with a through
hole 102c from the underside 102b.
[0111] Thus, a wavelength reduction effect of the dielectric base 7
can be achieved, and the size of the antenna element 3 can be
further reduced.
[0112] The other configurations, functions, and effects are similar
to those of the third preferred embodiment and thus will not be
described here.
Fifth Preferred Embodiment
[0113] FIG. 22 is a perspective view illustrating the upper side of
an antenna device according to a fifth preferred embodiment of the
present invention. FIG. 23 is a perspective view of a chip antenna
4. FIG. 24 is a perspective view illustrating the underside of the
antenna device. Note that the illustration of an antenna element 3
is omitted in FIG. 22.
[0114] In any one of the preferred embodiments described above, the
chip antenna 4 is disposed on the upper side 102a of the non-ground
region 102 such that the power feeder 110 for the chip antenna 2
can be shared with the chip antenna 4 through the conductive
pattern 41g. However, in the present preferred embodiment, a chip
antenna 4 does not share a power feeder with a chip antenna 2.
[0115] In other words, as illustrated in FIG. 22, a power feeder
120 different from a power feeder 110 is provided on the upper side
of a substrate 100. Furthermore, a through hole 102f is provided in
a non-ground region 102, while a conductive pattern 121 from the
power feeder 120 is connected to the through hole 102f. Then, as
illustrated in FIG. 24, a dielectric base 40 is disposed on an
underside 102b of the non-ground region 102, while a front
electrode section 41a of a radiation electrode 41 is connected to a
conductive pattern 122 drawn from the through hole 102f to the
underside 102b of the non-ground region 102.
[0116] With this configuration, the power feeders 110 and 120 are
provided to make different feeding points. Since this allows
isolation of a plurality of systems of the chip antenna 2 and the
chip antenna 4, the resonant frequencies thereof can be controlled
independently.
[0117] The other configurations, functions, and effects are similar
to those of the fourth preferred embodiment and thus will not be
described here.
Sixth Preferred Embodiment
[0118] FIG. 25 is an exploded perspective view of an antenna device
according to a sixth preferred embodiment of the present invention.
FIG. 26 is a diagram illustrating a state of quadruple
resonance.
[0119] Although each of the above-described preferred embodiments
deals with a triple-resonance antenna device achieved by the chip
antenna 2, the antenna element 3, and the chip antenna 4, the
number of resonance points is not limited to a specific number. As
in the case of the present preferred embodiment, another antenna
element 9 can be added to any one of the devices according to the
above-described preferred embodiments so as to form a
quadruple-resonance antenna device. Such a multiple-resonance
antenna device can still maintain its compactness and thin
profile.
[0120] That is, the antenna device of the present preferred
embodiment includes a chip antenna 2, an antenna element 3, and a
chip antenna 4 as in the case of the device of the second preferred
embodiment, and further includes an auxiliary element 31' on an
underside 102b of a non-ground region 102. Specifically, a through
hole 102g connected to an end of a conductive pattern 111 is
provided in an upper side 102a of the non-ground region 102, while
a metal support 31a' having a substantially L-shaped metal sheet
31b' is connected to the through hole 102g. This produces the
additional antenna element 9 using the auxiliary element 31'
separated from a base of a front electrode section 21a through the
through hole 102g as a total radiation electrode. The antenna
element 9 has a resonant frequency f4 corresponding to the length
and shape of the auxiliary element 31'.
[0121] Thus, in the antenna device of the present preferred
embodiment, signals at four different resonant frequencies f1, f2,
f3, and f4 can be sent and received by the chip antenna 2, antenna
element 3, chip antenna 4, and antenna element 9, respectively.
Therefore, as illustrated in FIG. 26, a return loss curve S'
showing the lowest return loss at four different frequencies f1,
f2, f3, and f4 can be obtained. Thus, the antenna device of the
present preferred embodiment allows a multiband transmission
capability adaptable to various applications.
[0122] The other configurations, functions, and effects are similar
to those of the second preferred embodiment and thus will not be
described here.
[0123] The present invention is not to be considered limited to the
preferred embodiments described above, and various modifications
and changes can be made within the scope of the present preferred
embodiment.
[0124] For example, although the auxiliary element of the antenna
element is disposed on the underside of the non-ground region in
the embodiments described above, it will be obvious that the
auxiliary element may be disposed on the upper side of the
non-ground region. In other words, the position, size, and number
of chip antennas and antenna elements are not limited to those
described in the above preferred embodiments, but may be
arbitrarily determined.
[0125] Additionally, although the dielectric base is used as a base
in the preferred embodiments described above, a magnetic base may
be used as a base of a chip antenna or the like.
[0126] While preferred embodiments of the present invention have
been described above, it is to be understood that variations and
modifications will be apparent to those skilled in the art without
departing the scope and spirit of the present invention. The scope
of the present invention, therefore, is to be determined solely by
the following claims.
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